Agglomerated particles of water-swellable addition polymers, preparation thereof and use thereof

ABSTRACT

Agglomerated particles of water-swellable addition polymers, the agglomerated particles having an average particle diameter of from 20 to 5000 μm and consisting of primary particles having an average particle diameter of from 0.1 to 15 μm, being preparable by polymerization of water-soluble monomers in the presence of from 1′ to 10% by weight of a regulator and at least 2000 ppm, each based on the monomers, of a crosslinking agent in the manner of a water-in-oil polymerization and subsequent azeotropic removal of water from the water-in-oil polymer emulsions, containing the primary particles, in the presence of agglomerating polyalkylene glycols which 
     (a) are obtainable by an addition reaction of C 2 -C 4 -alkylene oxides with alcohols, phenols, amines or carboxylic acids, and 
     (b) contain at least 2 polymerized alkylene oxide units, 
     and disintegrating into the primary particles on introduction into an aqueous medium, processes for preparing the agglomerated polymer particles and use of the agglomerated particles as thickeners for print pastes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to agglomerated particles ofwater-swellable addition polymers, the agglomerated particles having anaverage particle diameter of from 20 to 5000 μm and consisting ofprimary particles having an average particle diameter of from 0.1 to 15μm, being preparable by polymerization of water-soluble monomers in thepresence of regulators and of crosslinking agents in the manner of awater-in-oil polymerization and subsequent azeotropic removal of waterfrom the water-in-oil polymer emulsions, containing the primaryparticles, in the presence of agglomerating polyalkylene glycols which

(a) are obtainable by an addition reaction of C₂-C₄-alkylene oxides withalcohols, phenols, amines or carboxylic acids, and

(b) contain at least 2 polymerized alkylene oxide units,

and disintegrating into the primary particles on introduction into anaqueous medium, to processes for preparing the agglomerated polymerparticles, and to their use as thickeners for increasing the viscosityof aqueous systems.

2. Description of the Background

DE-C-36 41 700 discloses a process for preparing water-in-oil emulsionsof crosslinked, water-swellable addition polymers by polymerizingwater-soluble monomers and crosslinkers in the form of a water-in-oilemulsion using water-soluble azo initiators in the presence ofemulsifiers having an HLB value of at least 10. The polymers are notisolated, but are used directly in the form of the water-in-oil polymeremulsions as thickeners, for example for preparing textile print pastes.

EP-A-0 343 840 discloses finely divided crosslinked addition polymershaving a particle size of <20 μm. They are prepared by polymerizingwater-soluble monomers together with crosslinkers in the manner of awater-in-oil polymerization in the presence of free-radicalpolymerization initiators. The polymers are again not isolated; instead,the water is merely substantially distilled out of the emulsions and theemulsions are subsequently admixed with an oil-in-water emulsifier tofacilitate dispersion of the mixture in water. The polymers are used asthickeners in pigment print pastes. In pigment printing, the thickenerremains on the printed textile material together with the binder of thepigment print paste. However, the above-described thickeners are notsuitable for textile printing with print pastes which contain solubledyes, such as reactive dyes or disperse dyes, since such textile printsare subsequently washed and the thickener is not completely removable.The known thickeners remain on the textile material and give it a harshhand. The known thickeners are also electrolyte-sensitive, so that theyare not sufficiently effective on printing with reactive dyes, where theprint pastes contain relatively large amounts of salts as well as theionic dye.

WO-A-92/13912 discloses the agglomerated polymer particles described atthe beginning. The agglomerated polymer particles are present in theform of a powder. The crosslinked, water-swellable polymer powders areused as thickeners for aqueous systems, in particular as thickeners fortextile print pastes. However, these polymers have the disadvantage thatthey cannot be washed off and so impart too harsh a hand to the printedmaterial.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide novel substanceswhich, on use as thickeners for printing with soluble dyes, are readilywashed out of the printed material and which exhibit a good thickeningeffect in electrolyte-containing print pastes.

We have found that this object is achieved according to the presentinvention by agglomerated particles of water-swellable additionpolymers, the agglomerated particles having an average particle diameterof from 20 to 5000 μm and consisting of primary particles having anaverage particle diameter of from 0.1 to 15 μm, being preparable bypolymerization of water-soluble monomers in the presence of regulatorsand of crosslinking agents in the manner of a water-in-oilpolymerization and subsequent azeotropic removal of water from thewater-in-oil polymer emulsions, containing the primary particles, in thepresence of agglomerating polyalkylene glycols which

(a) are obtainable by an addition reaction of C₂-C₄-alkylene oxides withalcohols, phenols, amines or carboxylic acids, and

(b) contain at least 2 polymerized alkylene oxide units,

and disintegrating into the primary particles on introduction into anaqueous medium, when the water-in-oil polymerization is carried outusing the regulators in amounts from 1 to 10% by weight and thecrosslinkers in amounts of at least 2000 ppm, each based on themonomers.

The present invention also provides a process for preparing theabovementioned agglomerated polymer particles by polymerizingwater-soluble monomers in the aqueous phase of a water-in-oil emulsionin the presence of water-in-oil emulsifiers, polymerization initiators,regulators and crosslinkers and subsequent azeotropic removal of waterfrom the water-in-oil polymer emulsions in the presence of from 1 to 40%by weight, based on the monomers, of agglomerating polyalkylene glycolswhich

(a) are obtainable by an addition reaction of C₂-C₄-alkylene oxides withalcohols, phenols, amines or carboxylic acids, and

(b) contain at least 2 polymerized alkylene oxide units,

by agglomeration of the primary particles of the water-in-oil polymeremulsions and isolating the agglomerated polymer particles, by using theregulators in amounts from 1 to 10% by weight and the crosslinkers inamounts of at least 2000 ppm, each based on the monomers.

DETAILED DESCRIPTION OF THE INVENTION

The polymerization can be carried out with all water-solubleethylenically unsaturated monomers. These monomers are for exampleethylenically unsaturated C₃-C₆-carboxylic acids, such as acrylic acid,methacrylic acid, itaconic acid, maleic acid, fumaric acid andmethacrylic acid and also the amides thereof, especially acrylamide andmethacrylamide. Further suitable water-soluble monomers are for exampleacrylamidomethylpropanesulfonic acid, vinylsulfonic acid,vinylphosphonic acid and vinyllactic acid.

Further suitable water-soluble ethylenically unsaturated monomers aredi-C₁-C₃-alkylamino-C₂-C₆-alkyl (meth)acrylates, such asdimethylaminoethyl acrylate, dimethylaminoethyl methacrylate,diethylaminoethyl acrylate, diethylaminoethyl methacrylate,dimethylaminopropyl acrylate, dimethylaminobutyl acrylate,dimethylaminoneopentyl acrylate and dimethylaminoneopentyl methacrylate.The basic acrylates can be subjected to the polymerization in the formof the salts with inorganic acids or carboxylic acids having from 1 to 4carbon atoms or else in quaternized form. Also suitable are olefinicallyunsaturated nitriles, such as acrylonitrile.

It is also possible to use water-soluble diallylammonium compounds ofthe general formulae

where X⁻ is a halide ion, such as chloride, fluoride, bromide or iodide,or a hydroxide, nitrate, methosulfate, hydrogensulfate ordihydrogenphosphate ion, n and m are each integers from 1 to 2,preferably n=m=2,

Y is

 preferably an oxygen atom or a

 group, and

R¹, R², R³ and R⁴ are each a hydrogen atom or an alkyl radical havingfrom 1 to 6 carbon atoms and R⁵ and R⁶ are each H or an alkyl radical,which can be straight-chain or branched, having from 1 to 18 carbonatoms, preferably from 1 to 6 carbon atoms, or an aryl and/or benzylradical.

Such diolefinically unsaturated monomers include for exampledimethyldiallylammonium chloride, dimethyldiallylammonium bromide,diethyldiallylammonium chloride, methyl-tert-butyldiallylammoniummethosulfate, methyl-n-propyldiallylammonium chloride,dimethyldiallylammonium hydrogensulfate, dimethyldiallylammoniumdihydrogenphosphate, di-n-butyldiallylammonium bromide,diallylpiperidinium bromide, diallylpyrrolidinium chloride anddiallylmorpholinium bromide.

It is also possible to use N-vinylpyrrolidones, such asN-vinylpyrrolidone. It is also possible to use N-vinylformamide aswater-soluble monomer. It is either polymerized alone or copolymerizedin mixture with other ethylenically unsaturated monomers, for examplewith N-vinylpyrrolidone, acrylamide, methacrylamide, vinyl acetate,N-vinylimidazole, N-vinylimidazoline and/or dimethylaminoethyl acrylate.

Other suitable water-soluble monomers include N-vinylimidazoliumcompounds which can be characterized for example with the aid of thefollowing formula:

where R¹, R² and R³ may each be H or CH₃ and R¹ may also be C₂H₅, C₃H₇or C₄H₉, R⁴ may be H, C₁-C₆-alkyl, benzyl or

 and X⁻ may be an anion, such as Cl⁻, Br⁻, I⁻, methosulfate,ethosulfate, acetate, sulfate, hydrogensulfate or dihydrogenphosphate.Of this class of compounds, the unsubstituted N-vinylimidazole in saltform is preferred. Further suitable water-soluble monomers includeN-vinylimidazolines which can be characterized for example with the aidof the following general formula:

where

R¹=H, C₁-C₁₈-alkyl,

R⁵, R⁶=H, C₁-C₄-alkyl, Cl,

R²=H, C₁-C₁₈-alkyl,

R³, R⁴=H, C₁-C₄-alkyl, and

X⁻ is an acid radical.

Of this group of compounds, the polymerization is preferably carried outwith 1-vinyl-2-imidazoline salts of the formula II

where

R¹ is H, CH₃, C₂H₅, n- and i—C₃H₇, C₆H₅, and

X⁻ is an acid radical. X⁻ is preferably Cl⁻, Br⁻, SO₄ ²⁻, HSO₄⊖, H₂PO₄⊖,CH₃O—SO₃ ⁻, C₂H₅—O—SO₃ ⁻, R¹—COO⁻ and R²=H, C₁-C₄-alkyl or aryl.

The substituent X⁻ in the formulae I and II can in principle be anydesired acid radical of an inorganic or organic acid. The monomers ofthe formula I are obtained by neutralizing the free base, i.e.1-vinyl-2-imidazolines, with the equivalent amount of an acid. Thevinylimidazolines can also be neutralized with, for example,trichloroacetic acid, benzenesulfonic acid or toluenesulfonic acid. Aswell as salts of 1-vinyl-2-imidazolines it is possible to usequaternized 1-vinyl-2-imidazolines. They are prepared by reacting1-vinyl-2-imidazolines, which may be substituted in positions 2, 4 and5, with known quaternizing agents. Suitable quaternizing agents includefor example C₁-C₁₈-alkyl chlorides or bromides, benzyl chloride, benzylbromide, epichlorohydrin, dimethyl sulfate and diethyl sulfate. Thepreferred quaternizing agents are epichlorohydrin, benzyl chloride,dimethyl sulfate and methyl chloride.

Preferable water-soluble ethylenically unsaturated monomers are acrylicacid, methacrylic acid, acrylamide, methacrylamide,2-acrylamido-2-methylpropanesulfonic acid, N-vinylimidazole,N-vinylformamide, hydroxyethyl acrylate, hydroxypropyl acrylate,N-methylolacrylamide or mixtures thereof. The monomers can either bepolymerized alone to form homopolymers or else be polymerized in mixturewith one another to form copolymers. Of particular interest are forexample copolymers of acrylamide and acrylic acid, copolymers ofacrylamide and methacrylic acid, copolymers of methacrylamide andacrylic acid, copolymers of methacrylamide and methacrylic acid,copolymers of acrylamide, acrylic acid and2-acrylamido-2-methylpropanesulfonic acid, copolymers of acrylamide anddimethylaminoethyl acrylate, copolymers of acrylamide anddiethylaminoethyl methacrylate, and copolymers of methacrylamide anddimethylaminoethyl acrylate. The carboxylic acids and the otherethylenically unsaturated acids, such as vinylsulfonic acid andacrylamidomethylpropane sulfonic acid, can be used in the polymerizationeither in the form of the free acid, in partially neutralized or else incompletely neutralized form. The bases used for neutralizing thesemonomers are for example sodium hydroxide solution, potassium hydroxidesolution, ammonia, amines, such as triethylamine, butylamine,triethylamine, morpholine and ethanolamine.

The basic acrylates and methacrylates are preferably used in the homo-or copolymerization as salt or in quaternized form. The basic acrylatesand methacrylates are neutralized for example with the aid ofhydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid andcarboxylic acids, such as formic acid, acetic acid and propionic acid.The basic acrylates and methacrylates are also used in quaternized form.The quaternization products are obtained by quaternizing these compoundswith customary quaternizing agents, such as methyl chloride, ethylchloride, benzyl chloride, lauryl chloride, dimethyl sulfate, diethylsulfate or epichlorohydrin.

The polymerization of the water-soluble monomers is carried out in thepresence of at least 2000 ppm, based on all the monomers used, ofcrosslinkers. The crosslinkers contain at least two unconjugated,ethylenically unsaturated double bonds. Suitable crosslinkers includefor example N,N′-methylenebisacrylamide, polyethylene glycol diacrylatesand polyethylene glycol dimethacrylates, which are each derived frompolyethylene glycols having a molecular weight of from 126 to 8500,trimethylolpropane triacrylate, trimethylolpropane trimethacrylate,ethylene glycol diacrylate, propylene glycol diacrylate, butanedioldiacrylate, hexanediol diacrylate, hexanediol dimethacrylate,diacrylates and dimethacrylates of block copolymers of ethylene oxideand propylene oxide, doubly or triply acrylated or methacrylated adductsof ethylene oxide and/or propylene oxide with trimethylolpropane, atleast doubly acrylated or methacrylated polyhydric alcohols, such asglycerol or pentaerythritol, triallylamine, tetraallylethylenediamine,divinylbenzene, diallyl phthalate, polyethylene glycol divinyl ether,trimethylolpropane diallyl ether, polyethylene glycol divinyl ether,butanediol divinyl ether, pentaerythritol triallyl ether and/ordivinylethyleneurea and/or triallylmonoalkylammonium salts, for exampletriallylmethylammonium chloride. Preference is given to usingwater-soluble crosslinkers, for example N,N′-methylenebisacrylamide,polyethylene glycol diacrylates, polyethylene glycol dimethacrylates,pentaerythritol triallyl ether and/or divinylurea. The crosslinkers areused in an amount of at least 1000 ppm, preferably from 0.20% to 10% byweight, based on the total amount of monomers used in thepolymerization. The crosslinkers are used with particular preference inamounts from 0.2 to 0.5% by weight, based on the monomers.

The polymerization of the water-soluble monomers is carried out in thepresence of at least 1000 ppm of at least one crosslinker and at least1% by weight of at least one regulator, the stated amounts each beingbased on the monomers used. The regulator(s) used can be the compoundscustomarily suitable for this purpose, which limit the molecular weightof polymers being polymerized, for example alcohols, salts of hydrazineand of hydroxylamine, formic acid, alkali metal and ammonium salts offormic acid and organic compounds which contain sulfur in bonded formsuch as, respectively organic, sulfides, disulfides, polysulfides,sulfoxides, sulfones and mercapto compounds. The followingpolymerization regulators are mentioned by way of example: di-n-butylsulfide, di-n-octyl sulfide, diphenyl sulfide, thiodiglycol,ethylthioethanol, diisopropyl disulfide, di-n-butyl disulfide,di-n-hexyl disulfide, diacetyl disulfide, diethanol sulfide, di-t-butyltrisulfide and dimethyl sulfoxide. Preferable polymerization regulatorsare mercapto compounds, dialkyl sulfides, dialkyl disulfides and/ordiaryl sulfides. Examples of these compounds are ethyl thioglycolate,cystein, 2-mercaptoethanol, 1,3-mercaptopropanol,3-mercaptopropane-1,2-diol, 1,4-mercaptobutanol, thioglycolic acid,3-mercaptopropionic acid, mercaptosuccinic acid, thioglycerol,thioacetic acid, thiourea and alkyl mercaptans such as n-butylmercaptan, n-hexyl mercaptan or n-dodecyl mercaptan. Particularlypreferable polymerization regulators are isopropanol, formic acid andits alkali metal and ammonium salts, thioglycolic acid and its alkalimetal and ammonium salts and also all regulators which have a similartransfer constant to thioglycolic acid. The polymerization regulatorsare preferably used in amounts of from 0.25 to 10% by weight, based onthe monomers used in the polymerization. The polymerization can ofcourse also be carried out with mixtures of polymerization regulators.

In order to polymerize the monomers, they are first dissolved in water.The concentration of the monomers in the aqueous solution is from 20 to80, preferably from 30 to 60, % by weight. The aqueous solution is thenemulsified in an inert hydrophobic liquid (oil phase) in the presence ofat least one water-in-oil emulsifier with formation of a water-in-oilemulsion. Virtually all water-immiscible liquids which do not interferein the polymerization may be used as inert hydrophobic liquids.Aliphatic and aromatic hydrocarbons or mixtures of aliphatic andaromatic hydrocarbons are preferably used for this purpose. Suitablealiphatic hydrocarbons are, for example, pentane, hexane, heptane,octane, nonane, decane, cyclohexane, decalin, methylcyclohexane,isooctane and ethylcyclohexane. Aromatic hydrocarbons which are used asthe hydrophobic liquid in the reverse suspension polymerization are, forexample, benzene, toluene, xylene and isopropylbenzene. It is of coursealso possible to use halohydrocarbons, such as tetrachloroethane,hexachloroethane, trichloroethane and chlorobenzene. Cyclohexane orhydrocarbons boiling within the range from 60 to 170° C. are preferablyused. The oil phase accounts for from 15 to 70, preferably from 20 to60, % by weight of the water-in-oil polymer emulsion.

The relevant known water-in-oil emulsifiers are used for dispersing theaqueous monomer solution in the oil phase. These are, for example,sorbitan esters, such as sorbitan monostearate, sorbitan monooleate,sorbitan palmitate and sorbitan laurate, and glyceryl esters whose acidcomponent is derived from C₁₄C₂₀carboxylic acids. Further suitableemulsifiers are the water-in-oil emulsifiers which are disclosed inDE-B-25 57 324 and are obtainable by reacting

A) C₁₀-C₂₂-fatty alcohols with epichlorohydrin in a molar ratio of from1:0.5 to 1:1.5 to give glycidyl ethers,

B) reacting the glycidyl ethers with (1) saturated C₂-C₆-alcoholscontaining from 2 to 6 OH groups or (2) monoethers thereof withC₁₀-C₂₂-fatty alcohols, in a molar ratio of glycidyl ether to (1) or (2)of from 1:0.5 to 1:6 in the presence of acids or bases, and

C) alkoxylating the reaction products according to (B) with at least oneC₂-C₄-alkylene oxide in a molar ratio of from 1:1 to 1:6.

Further suitable emulsifiers are constructed from at least onehydrophilic and at least one hydrophobic block, the blocks each havingmolecular weights of more than 500 to 100,000, preferably from 550 to50,000, very particularly preferably from 600 to 20,000. The emulsifierscan have a comblike or linear construction. Linear block copolymers ofthe type AB or of the type ABA, where A is a hydrophobic polymer blockand B is a hydrophilic polymer block, are known; cf. EP-A-0 000 424 andEP-A-0 623 630. Preferably the emulsifiers to be used are soluble in thewater-immiscible solvent used.

The hydrophilic blocks are separately soluble in water at 25° C. to morethan 1%, preferably 5% by weight. Examples are blocks constructed fromethylene oxide, propylene oxide or butylene oxide units, optionallyintermixed. The hydroxyl groups of the alkylene oxide blocks can beadditionally modified by sulfate or phosphate ester groups. Suitablefurther blocks are derived from polytetrahydrofuran,poly(1,3-dioxolane), poly(2-methyl-2-oxazoline), polyethyleneimine,polyvinyl alcohol, polyvinylamine, polyvinylpyrrolidone,poly(meth)acrylic acid, polyamidoamines, gelatin, cellulose derivativesor starch. Particular preference is given to blocks based on ethyleneoxide and/or propylene oxide units.

The hydrophobic parts of the emulsifiers consist for example of blocksof polystyrene, polyalkyl (meth)acrylates, polysiloxanes,poly(hydroxyalkanoic acids) such as polycondensates of2-hydroxypropanoic acid, 2-hydroxybutanoic acid, 2-hydroxyisobutanoicacid, 2-hydroxyheptanoic acid, 10-hydroxydecanoic acid,12-hydroxydodecanoic acid, 12-hydroxystearic acid,16-hydroxyhexadecanoic acid, 2-hydroxystearic acid, 2-hydroxyvalericacid or the corresponding condensates obtained from lactones,condensates of diols and dicarboxylic acids such as polyethyleneadipate, polylactams such as polycaprolactam, polyisobutylene orpolyurethanes. Preference is given to blocks of polystyrene, polymethylmethacrylate, polybutyl methacrylate, polyhydroxyalkanoic acids havingmore than 10 carbon atoms in the alkane unit, polydimethylsiloxanes orpolyisobutylenes. Very particular preference is given to blocks ofpolystyrene, polyhydroxy fatty acids such as poly(12-hydroxystearicacid) or polydimethylsiloxanes.

Of these compounds, preference for use as emulsifier is given to thoseblock copolymers where

A is a hydrophobic polymer block selected from the group consisting ofpolystyrene, poly(hydroxycarboxylic acids), polydimethylsiloxanes andpolyisobutylenes, and

B is a hydrophilic polymer block from the group of theC₂-C₄-polyalkylene glycols.

The suitable water-in-oil emulsifiers have an HLB value of not more than8. The HLB value is understood as meaning the hydrophilic/lipophilicbalance of the emulsifier, cf. W. C. Griffin, J. Soc. Cosmet. Chem. 1(1949), 311. The water-in-oil emulsifiers are used in an amount of from2 to 20, preferably from 5 to 15, % by weight, based on the monomersused. The water-in-oil emulsifiers described in the stated DE-B-25 57324 are preferably used.

Suitable free radical polymerization initiators which may be used areall conventionally used polymerization initiators. Water-solubleinitiators, such as alkali metal or ammonium peroxodisulfates, hydrogenperoxide, diacetyl peroxodicarbonate, dicyclohexyl peroxodicarbonate,tert-butyl perpivalate, dilauroyl peroxide, dibenzoyl peroxide,tert-butyl per-2-ethylhexanoate, tert-butyl permaleate,bis(tert-butylperoxo)cyclohexane, tert-butyl peracetate, dicumylperoxide, di-tert-amyl peroxide, di-tert-butyl peroxide, cumylhydroperoxide, tert-butyl hydroperoxide and p-menthane hydroperoxide,and azo initiators, such as 2,2′-azobis(2-methyl-N-phenylpropionamidine)dihydrochloride, 2,2′-azobis(2-methylpropionamidine) dihydrochloride,2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(isobutyronitrile),2,2′-azobis(2-amidinopropane) dihydrochloride and 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, are preferred. Preferredinitiators are alkali metal and ammonium persulfates, tert-butylperpivalate, tert-butyl per-2-ethylhexanoate,2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2-amidinopropane)dihydrochloride, azobis(isobutyronitrile) and2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride. It ispossible to use either a single initiator or a mixture of a plurality ofinitiators. The choice of the initiators depends primarily on thetemperature at which the polymerization is carried out. Salts of heavymetals, for example copper, cobalt, manganese, iron, nickel and chromiumsalts, and/or organic compounds, such as benzoin, dimethylaniline orascorbic acid, and reducing agents, for example alkali metal disulfiteor sodium formaldehyde sulfoxylate, may additionally be used togetherwith at least one of the abovementioned free radical polymerizationinitiators. Such mixtures of initiators permit polymerization at lowertemperatures. The reducing component of redox initiators may be, forexample, sodium sulfite, sodium bisulfite, sodium formaldehydesulfoxylate or hydrazine. From 100 to 10,000 ppm, preferably from 100 to2000 ppm, based on the monomers used in the polymerization, of apolymerization initiator or of a mixture of a plurality ofpolymerization initiators are required. The stated amounts of initiatorcorrespond to about 0.002-0.3 mol %, based on the monomers used, ofinitiator.

The polymerization of the water-soluble monomers is preferably carriedout in the additional presence of at least one oil-in-water emulsifier.The use of this group of emulsifiers permits the preparation ofparticularly finely divided water-in-oil polymer emulsions which arestable to sedimentation. Examples of suitable oil-in-water emulsifiersare all wetting agents which have an HLB value of at least 10. Thisgroup of emulsifiers comprises essentially hydrophilic water-solublecompounds, such as ethoxylated alkylphenols or ethoxylated fattyalcohols. Products of this type are obtained, for example, by reactingC₈-C₁₂-alkylphenols or C₈-C₂₂-fatty alcohols with ethylene oxide.Preferably, C₁₂-C₁₈-fatty alcohols are ethoxylated. The molar ratio ofalkylphenol or fatty alcohol to ethylene oxide is in general from 1:5 to1:20. Further suitable emulsifiers are, for example, alkoxylated fattyamines. If the emulsifiers having an HLB value of 10 or higher are usedin the polymerization, they are employed, for example, in amounts offrom 1 to 20, preferably from 2 to 15, % by weight, based on themonomers to be polymerized.

The polymerization of the monomers is carried out in the aqueous phaseof a water-in-oil emulsion in the presence of water-in-oil emulsifiersand optionally protective colloids which are customarily used in theinverse suspension polymerization and. optionally oil-in-wateremulsifiers and also in the presence of free radical polymerizationinitiators.

The water-in-oil polymer emulsions are azeotropically stripped of waterin the presence of agglomerating polyalkylene glycols.

The removal of water from the water-in-oil polymer emulsions is carriedout under the conditions indicated in WO-A-92/13912. The azeotropicremoval of water leaves agglomerations of primary particles which,according to sieve analysis, have an average particle diameter of fromabout 20 to 5000, preferably from 50 to 2500, μm. The agglomeratedpolymer particles contain primary particles having an average particlediameter of from 0.1 to 15 μm. The water present in the water-in-oilpolymer emulsions is removed by azeotropic distillation to at least 80%,preferably to an extent of up to 95-99%. Small amounts of water whichremain in the polymers present no problems. On introducing agglomeratedparticles dried by azeotropic distillation into water they disintegrateinto the primary particles.

The polyalkylene glycols which are suitable as agglomeration assistantsare obtainable, for example, by subjecting the suitable alkylene oxides,ie. ethylene oxide, propylene oxide, 1,2-butylene oxide or isobutyleneoxide, and tetrahydrofuran to an addition reaction with alcohols,phenols, amines or carboxylic acids. The stated alkylene oxides andtetrahydrofuran may be polymerized either alone or as a mixture. Ifmixtures are used, polymeric compounds in which the alkylene oxide unitsare randomly distributed are obtained. However, the alkylene oxides mayalso be reacted in a conventional manner to give block copolymers.Homopolymers of ethylene oxide are obtained, for example, by subjectingethylene oxide to an addition reaction with ethylene glycol. For thepreparation of homopolymers of propylene oxide, propylene oxide issubjected to an addition reaction with 1,2-propylene glycol,1,3-propylene glycol or a mixture of the stated isomers. Thehomopolymers of other alkylene oxides are prepared in a correspondingmanner.

Block copolymers are prepared, for example, by first subjecting ethyleneoxide to an addition reaction with ethylene glycol and allowing thereaction to go to completion and then subjecting propylene oxide to anaddition reaction with the product under the conventional conditions,ie. by catalysis with alkali metal hydroxides or calcium oxide. Here,there are many possibilities for varying the sequence of the blocks ofalkylene oxide units. For example, an ethylene oxide block may befollowed by a propylene oxide block and the latter by an ethylene oxideblock. Polyalkylene glycols which contain an ethylene oxide block, apropylene oxide block and a butylene oxide block or polyalkylene glycolsin which a propylene oxide block is followed by an ethylene oxide blockor polyalkylene oxides in which a butylene oxide block is followed by apropylene oxide block and, if desired, an ethylene oxide block may alsobe used as agglomeration assistants.

The terminal groups of the polyalkylene glycols thus formed may beblocked at one or both ends. Polyalkylene glycols blocked at one end areobtained, for example, by subjecting alkylene oxides to an additionreaction with alcohols, phenols, amines or carboxylic acids. Examples ofsuitable alcohols are monohydric C₁-C₂₂-alcohols, for example methanol,ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-octanol,isooctanol and stearyl alcohol. Polyhydric alcohols, for example asstated above, ethylene glycols or propylene glycols and glycerol,pentaerythritol and 1,6-hexanediol, may also be used as alcohols. Thealkylene oxides may also be subjected to an addition reaction withphenol and substituted phenols, such as C₁-C₁₈-alkylphenols. Amines arealso suitable for blocking terminal groups, for example C₁-C₁₈-alkyl- ordialkylamines and diamines, preferably ethylenediamine. Commercialproducts which are obtainable, for example, by successive additionreactions of ethylene oxide and propylene oxide with ethylenediamine areof particular interest here. Thioalcohols, such as mercaptoethanol,mercaptopropanols and mercaptobutanols, may also be alkoxylated. Theterminal OH groups of the polyalkylene glycols may also be replaced, forexample, by amino groups. Further polyalkylene glycols which aresuitable as agglomeration assistants are those whose terminal OH groupsare etherified or esterified.

The suitable polyalkylene glycols contain at least 2 polymerizedalkylene oxide units. Suitable agglomeration assistants are, forexample, polyethylene glycols, polypropylene glycols, block copolymerscomprising ethylene oxide and propylene oxide blocks and having thestructure EO-PO, PO-EO-PO or EO-PO-EO, polyethylene glycolsmonoetherified or dietherified with C₁-C₄-alcohols and those compoundswhich are obtainable by subjecting first ethylene oxide and thenpropylene oxide, or first propylene oxide and then ethylene oxide, to anaddition reaction with ethylenediamine. Suitable polyalkylene glycolswhich have an agglomerating effect are, for example, diethylene glycol,triethylene glycol, tetraethylene glycol, pentamethylene glycol,hexaethylene glycol, heptaethylene glycol, octaethylene glycol,diethylene glycol dimethyl ether, diethylene glycol monomethyl ether,diethylene glycol diethyl ether, diethylene glycol monoethyl ether,triethylene glycol mono- and dimethyl ether, triethylene glycol mono-and diethyl ether, dialkylene glycol dibutyl ether, diethylene glycolmonobutyl ether, diethylene glycol monopropyl ether, diethylene glycoldipropyl ether, EO-PO block copolymers having average molecular weightsof from 120 to 2 million, PO-EO-PO block copolymers having averagemolecular weights of from 178 to 2 million and EO-PO-EO block copolymershaving average molecular weights of from 134 to 2 million, dipropyleneglycol diacetate, diethylene glycol diacetate, dipropylene glycolmonoacetate, diethylene glycol monoacetate, dipropylene glycol dimethylether and dipropylene glycol monomethyl ether. The stated molecularweights are number average molecular weights. The agglomerationassistants are preferably used in amounts of from 5 to 20% by weight,based on the polymer present in the water-in-oil emulsion.

After the azeotropic removal of water in the presence of thepolyalkylene glycols, agglomerated polymer particles are present whichcan be readily isolated, for example by filtration, decanting of thehydrocarbon oil or centrifuging. Adhering hydrocarbon oil can readily beremoved from the agglomerated polymer particles, for example by dryingin a drying oven, preferably at relatively high temperatures and underreduced pressure.

The pulverulent agglomerated polymer particles are used as thickenersfor increasing the viscosity of aqueous systems. They are suitable forexample as thickeners for print pastes for printing textiles or else asthickeners for aqueous polymer dispersions which find utility forexample as binders for paper coating compositions or as binders inpaints. Particular preference is given to the use of the agglomeratedpolymer particles as thickeners in print pastes containing at least onereactive dye and/or a disperse dye. Those polymers with a monomer havingan acid group, for example acrylic acid, methacrylic acid or2-acrylamido-2-methylpropanesulfonic acid, are preferably used in theform of the sodium or potassium salts, or the polymers with the acidgroups are preferably neutralized with sodium hydroxide solution orpotassium hydroxide solution. The sodium or potassium salts of thepolymers are particularly easy to wash off printed textiles comparedwith the corresponding ammonium salts.

The print pastes have the customary construction. Per 1000 parts byweight the finished print paste contains for example from 500 to 989parts by weight of water, from 1 to 200 parts by weight of at least onereactive dye and/or at least one disperse dye and from 10 to 100 partsby weight of a thickener to be used according to the present invention.Reactive dyes and disperse dyes are commercially available. Dispersedyes are synthetic dyes which are sparingly soluble in water and whichare commercially available in the form of fine suspensions stabilizedwith dispersions. On printing the dye particles diffuse into the fiberto form a solid solution therein.

Reactive dyes contain a reactive component (hook) as well as achromophore. On printing the dye becomes attached through chemicalreaction with functional groups of the fiber. Reactive dyes aredescribed for example in detail in the Colour Index, 1982, 3^(rd)Edition, Vol. 5, published by the Society of Dyers and Colourists, H.Charlesworth & Co. Ltd., Huddersfield. To print and dye textilematerials made of cellulose, the customary amounts of dyes and anyassistants to be used are used in the customary amounts. The reactivedyes can have various reactive groups, or hooks, for example vinylsulfone, monochlorotriazine or β-sulfatoethylsulfonyl groups. The dyescan belong to various dye classes, for example azo dyes, metal complexazo dyes, anthraquinone dyes, phthalocyanine dyes, phenacene andazomethine dyes.

EXAMPLES Preparation of the Water-In-Oil Polymer Emulsions

Following DE-C-36 41 700, a 2 l capacity polymerization vessel equippedwith horseshoe stirrer, thermometer, nitrogen inlet and nitrogen outletis charged with the respectively below-described monomer emulsions. Thepolymerizable mixture is then emulsified for 30 min at room temperatureunder nitrogen at a stirrer speed of 200 rpm with half the amount ofinitiator. The reaction mixture is then heated to a temperature withinthe range from 55 to 70° C. and polymerized in that range for 1.5 h.Then the remainder of the initiator is added and the reaction mixture isheated at 65° C. for a further 2 h with stirring.

Example 1

The monomer emulsion is prepared by initially charging acrylic acid andneutralizing it with aqueous sodium hydroxide solution to a pH of 7.Then the other components are added together with sufficient aqueoussodium hydroxide solution so that the pH is 8. Sufficient water is thenadded for the total amount of the reaction mixture to be 1000 g.

Composition of the Monomer Emulsions in the Preparation of the W/OPolymer Emulsions

Polymer 1

308 g of cyclohexane

17.6 g of a water-in-oil emulsifier obtainable by reaction of

A) oleyl alcohol with epichlorohydrin in a molar ratio of 1:1 to formoleyl glycidyl ether,

B) reaction of the oleyl glycidyl ether with glycerol in a molar ratioof 1:1 in the presence of BF₃-phosphoric acid at a temperature of 80° C.and removal of the catalyst with the aid of a basic ion exchanger, and

C) ethoxylation of the reaction product of (B) with 2 mol of ethyleneoxide,

2.6 g of a surfactant obtainable by reaction of a C₁₃/C₁₅ oxo alcoholwith 6 mol of ethylene oxide and 4 mol of propylene oxide,

153.8 g of acrylic acid

13.2 g of acrylamide

13.2 g of N-vinylpyrrolidone

3.6 g of thioglycolic acid

0.08 g of penta sodium salt of diethylenetriaminepentaacetic acid

0.36 g of methylenebisacrylamide

Initiator:

0.092 g of 2,2′-azobis(2-amidinopropane) dihydrochloride

Polymer 2

The composition differs from the composition of the monomer emulsionindicated for polymer 1 only in that no N-vinylpyrrolidone is used.

Polymer 3

The preparation of polymer 1 is repeated except that acrylic acid andN-vinylpyrrolidone are used as monomers and the neutralization iscarried out with potassium hydroxide solution.

Polymer 4

The procedure for polymer 1 is repeated except that the 3.6 g ofthioglycolic acid (20,000 ppm) are replaced by 5.4 g of formic acid({circumflex over (=)}25,000 ppm).

Comparison 1

This is the W/O polymer 1 indicated in WO-A-92/13912, which contains92.1% of acrylic acid and 7.9% of acrylamide.

The above-described polymers 1 to 4 and the polymer of comparison 1 areeach admixed with 10 g of an agglomerating polyethylene glycol having anaverage molecular weight of 300 and—as described inWO-A-92/13912—subjected to an azeotropic removal of water. After thewater has been removed, the polymer suspensions are filtered and theagglomerated polymers are dried in a vacuum drying cabinet at 50° C. Theagglomerated polymers 1 to 4 and the agglomerated polymer of ComparativeExample 1 are obtained.

APPLICATION EXAMPLES Example 1

410 g of the agglomerated polymer 1 are sprinkled into 7914 g of waterof 15° German hardness with stirring. The agglomerated polymer isreadily dispersible therein and does not clump. After 3 minutes of highspeed stirring a homogeneous paste is obtained.

Then, with stirring,

1200 g of urea

250 g of sodium carbonate

100 g of sodium m-nitrobenzenesulfonate

100 g of the pulverulent blue reactive dye of CI No. 61205 are added insuccession

and the mixture is homogenized at 10,000 rpm for 3 min.

The product obtained is a print paste having a viscosity of 40 poise.The addition of the reactive dye brought about a decrease in theviscosity of 32 poise.

The print paste obtained was then printed with a rotary screen printingmachine onto a cotton fabric. The printed fabric was dried at atemperature of 110° C. for 2 min and then fixed in saturated steam at102° C. for 10 min. The fabric is subsequently rinsed in succession withwater at 20° C. and water at 60° C. and boiled with a wash liquor whichcontains 2 g/l of an addition product of 8 mol of ethylene oxide with 1mol of nonylphenol. After renewed rinsing at 20° C., the fabric isdried. The product obtained is a very strong, level and crisp printhaving good rub and wet fastness properties.

To evaluate the wash-off characteristics of the thickener, a strip ofabout 5×15 cm of the fixed, unwashed print is treated in distilled waterat 80° C. in a tester from Ahiba AG (Switzerland), model WBRG 7. After 5min the wet strip was removed from the instrument. It felt neitherslippery nor slimy. The strip was dried at 110° C. for 2 min. It thenhad a very soft smooth hand.

Example 2

305 g of agglomerated polymer 1 are sprinkled into 9395 g of tap waterof 15° German hardness with stirring. The polymer is readily dispersibleand does not clump. After 3 minutes of high speed stirring a homogeneouspaste is obtained. Then 300 g of the blue disperse dye C.I. DisperseBlue 87 in the liquid, 20% strength, nonionic finished commercial formare added with stirring and the batch is stirred with a high speedstirrer at 10,000 rpm for 3 min.

The print paste is then printed with a rotary screen printing machineonto a polyester satin fabric. The printed material is dried at 100° C.for 3 min and then subjected for 10 min to a superheated steam fixationat 170° C. The material is then rinsed with water at 20° C. andsubsequently washed at 60° C. with a wash liquor containing 1 g/l of anaddition product of 8 mol of ethylene oxide with 1 mol of nonylphenoland 1 g/l of 50% strength aqueous sodium hydroxide solution. Afterrenewed rinsing at 20° C. the material is dried. The result obtained isa very strong, level and crisp print having good rub and wet fastnessproperties. The wash-off characteristics of the thickener from theprinted material are tested as described in Example 1. After the 5minute treatment in distilled water a wet test strip feels neitherslippery nor slimy. The test strip is then dried at 110° C. for 2 min.It then had a very soft, smooth hand.

Examples 3 to 5

Example 1 was repeated with agglomerated polymers 2 to 4 in the amountsindicated in each case in the Table below.

TABLE Viscosity Agglomerated Amount used Viscosity of decrease onpolymer No. Thickener Tap water print paste addition of dye 2 380 g 7970g 40 poise 43 poise 3 440 g 7910 g 40 poise 28 poise 4 410 g 7940 g 40poise 33 poise The prints and the wash-off characteristics are in allcases similar to those of Example 1.

Comparative Example 1

Example 1 was repeated by using 320 g of the agglomerated polymer of thecomparison in 8030 g of water of 15° German hardness. The viscosity ofthe print paste was 40 poise, the decrease in the viscosity on additionof the dye was 43 poise. The prints are very similar to those of Example1, but the wash-off characteristics of the thickener are poor. Thewash-off characteristics were tested as indicated in Example 1. However,after a treatment of 5 min in the tester, the printed fabric was veryslippery and greasy. The treatment was therefore continued for a further15 min, but no improvement was obtained. The prints were still slippery.The fabric was then dried at 102° C. for 2 min. Afterwards it was stiffand had a harsh hand.

We claim:
 1. Agglomerated particles of water-swellable additionalpolymers, the agglomerated particles having an average particle diameterof from 20 to 5000 μm and consisting of primary particles having anaverage particle diameter of from 0.1 to 15 μm, prepared bypolymerization of water-soluble monomers in the presence of regulatorsand of cross linking agents in the manner of a water-in-oilpolymerization and subsequent azeotropic removal of at least 80% of thewater from the water-in-oil polymer emulsions, containing the primaryparticles, in the presence of agglomerating polyalkylene glycols, (a)said polyalkylene glycols are prepared by an addition reaction ofC₂-C₄-alkylene oxides with alcohols, phenols, amines or carboxylicacids, and (b) contain at least 2 polymerized alkylene oxide units, andsaid agglomerated particles have the property of disintegrating into theprimary particles on introduction into an aqueous medium, wherefore thewater-in-oil polymerization is carried out using the regulators inamounts from 1 to 10% by weight and the crosslinkers in amounts of atleast 1000 ppm, each based on the monomers.
 2. A process for preparingagglomerated particles of water-swellable addition polymers as claimedin claim 1 comprising polymerizing water-soluble monomers in the aqueousphase of a water-in-oil emulsion in the presence of water-in-oilemulsifiers, polymerization initiators, regulators in amounts from 1-10%by weight and crosslinkers in amounts of at least 1000 ppm, each basedon the total amount of monomer, followed by azeotropic removal of atleast 80% of the water from the water-in-oil polymer emulsions in thepresence of from 1 to 40% by weight, based on the polymers, ofagglomerating polyalkylene glycols which (a) are obtained by an additionreaction of C₂-C₄-alkylene oxides with alcohols, phenols, amines orcarboxylic acids, and (b) contain at least 2 polymerized alkylene oxideunits, thereby agglomerating the primary particles of the water-in-oilpolymer emulsion, then isolating the agglomerated polymer particles. 3.A process as claimed in claim 2, wherein the water-soluble monomers areacrylic acid, methacrylic acid, acrylamide, methacrylamide,N-vinylpyrrolidone, N-vinylimidazole, N-vinylformamide,2-acrylamido-2-methylpropanesulfonic acid, hydroxyethyl acrylate,hydroxypropyl acrylate, N-methylolacrylamide or mixtures thereof.
 4. Amethod of thickening an aqueous composition comprising combining theaqueous composition with the agglomerated particles of claim 1.